Weed killer



Patented Jan. 20, 1953 OFFICE WEED KILLER Frank J. Sowa, Craniord, N. J.

No Drawing.

Application January 4, 1950,

Serial No. 136,850

7 Claims.

This invention relates to herbicides such as weed killers and is directed particularly to compositions containing monoammino boron trifiuoride (NHa-BFs) as an essential active ingredient.

Many types of weed killers are known, but they 3 generally are found objectionable or inadequate for many purposes. Thus for example sodium chlorate is an excellent weed killer, but weeds treated with this composition are highly inflammable, and therefore sodium chlorate is not suitable for use along the right of way of railroads or power lines or in forested areas. On the other hand, sodium arsenite, potassium cyanate and phenylmercury compounds are also effective as weed killers, but because of their poisonous nature they cannot be used with safety in areas where cattle or other animals may be grazing. Furthermore, practically all of the common weed killer compositions are only temporarily effective and therefore must be applied frequently to weed infested areas. a

I have discovered that compositions containing monoammino boron trifiuoride are not only effective as weed killers, but they have the most unusual property of being selective in their killing action when used in limited concentrations, whereas in higher concentrations they actually impart sterility to the soil whereby a single application may prevent the growth of weeds on tennis courts, driveways or elsewhere for a period of two or three years or more. Furthermore, these compositions are effective fire retardants so that the dead weeds are substantially non-inflammable. On the other hand, the compositions are not actively poisonous and there is some evidence that weeds treated therewith are actually repellent or repulsive to many animals.

One of the'objects of the invention is to provide' novel herbicidal compositions containing monoamniino boron trifiuoride as an esse'ntialactive ingredient.

A further object of the invention is to provide herbicidal compositions which impart sterility to the soil when used in relatively high concentrations, but which are selective in their action when used inlimited concentrations.

vAnother object of the invention is to provide nove1 methods for destroying crab grass.

These and other objects and features of the present invention will appear from the following description thereof in which reference is made to preferred compositions and methods of using the same for the purpose of indicating the nature of the invention, but without intending to limit the invention thereby.

The compositions of the present invention contain as their essential active ingredient monoammino boron trifiuoride (NHs-BFs).

The preferred compositions are in the form of aqueous solutions which include'non-ionic type wetting agents. Typical of those wetting agents that have been employed to advantage are poly ethylene ether of fatty alcohols, polyethylene glyco1 condensation products and long chain alcohol sulfates or in fact substantially any of the conventional wetting agents otherthan the salts of organic acids. Those wetting agents which consist of sodium salts of organic acids, such as the long chain fatty acids or sulfated oils are generally found to be incompatible with aqueous solutions of monoammino boron trifiuoride and therefore are not ordinarily employed. The amount of wetting agent used in preferably sulficient to produce an aqueous solution containing 1% of the monoammino boron trifiuoride and having a surface tension below about 40 dynes per centimeter at 23 C. although solutions having a surface tension up to dynes per centimeter may be used.

When the composition is in the form of an aqueous solution for killing of grasses or weeds and it is desired to impart sterility to the soil in the area treated the amount of monoammino boron trifiuoride applied per acre ranges from 150 to 400 lbs. However, when the composition is to I be used for selective killing of weeds such as crab grass and plantain the concentration of the monoammino boron trifiuoride should be from- "the plants. The amount of wetting agent used is preferably equal to 0.10 to -l% by weightof' the solution or about 10 to of the weightof ,monoammino boron trifiuoride. I

Example 1 One typical composition has the following formula:

' Parts by weight NHa'BFs 1 Wetting agent 1% Water 100 In tests conducted at the Rutgers University Agriculture School it was found that a single application of this composition by means of a single nozzle hand sprayer at pressures ranging from 15 to 30 pounds and at the rate of 16 gallons per 1000 square feet to an area infected with crab grass served to kill 94.9% of the crab grass and concentrations.

3 although other grasses were at first discolored they eiiectively recovered. Further it was found that when three successive applications were made in the same manner, applying the solution at the rate of 25 lbs. of the complex per acre, approximately 96% of the crab grass was killed while substantially 98% of the crab grass was killed when making two applications at therate.

of 40 lbs. to the acre but the discoloration is moderate.

Example 2 Another typical composition is as follows? Parts by weight This composition is effective in killing substantiailyall weeds-in the area treated and when the;concentration of the NHs -BF3' is in the neighborhood of 110% it is an excellent agent for'use in; kiliingpoisonivy. The composition is sprayed on theafffected area-at-the rate of "16 gallons per 1000 square feet and will impart sterility to the soilfor a: period of many'months.

'I'he.amount of the composition required to obtain the best results in'any application varies considerably and is dependent on numerous factors. Thus if the crab grassconsists of' young tender 'SI'IOOtSTit' isinot necessary to use as high a concentration: per acre as when the plants are mature and; strong. The composition also appears'to be moreeifective'when' a plied on a hot dry day than when the air is moist and cool.

In preparing the products for shipment and stora e it is preferableto' mix the monoammino boron trifiuoride thoroughly with the wetting agent using an anhydrous form of a non-ionic wetting agent so as to avoid separation on standing of" a layer of saturated aqueous solution. Typical products of this type contain '75 parts by weightof monoammino boron trifiuoride and 1mm 'to '50 parts by weight of anhydrous polyethylene. glycol .condensation product.

'While the compositions of the present invention may be used in the form of an aqueous solution without adding a wetting agent the surface tension of such solutions is relatively high and they therefore. have to be applied more heavily totinsure thorough wetting of the surfaces. offtheweeds and absorption thereof by theroot systemcof the plant. In such cases application is generally. made at the rate of 200 ibsror .more'per acreand selective killing of" crab grass. and plantainis not possible, at such high In fact sterility of the. soil usually results. from. such heavy application of the composition.

Any of the foregoing compositions when applied for killing weeds is also active as a fire retardant, whereas the dried weeds are not injurious or irritating to the skin.

While various compositions have been described and typical methods for using such compositions havebeen cited it will be apparent that they may be varied considerably by the addition of other agents'theretoand by their application in other ways to areas in which weeds or vegetation is to bekilled. In view thereof it should be under- 4 stood that the examples cited above are intended to be illustrative only and are not intended to limit the scope of the invention.

I claim:

1. The. method of killing weeds which comprises the step of applying thereto an aqueous solution containing from about 0.10 to 10% by weight of monoammino boron trifluoride at the rate of about 16 gallons of solution per 1000 square feet.

2. The method of killing weeds which comprises. the step of applying thereto an aqueous solution containing from about 0.10 to 10% by weight of monoammino boron trifiuoride together with from about 0.10 to 1% by weight of a wettingagent, atthe-rate ofrabout lfigallons per 1000 square feet. 4

3. The method of imparting, sterility to soi which comprises thfifitep. of applying. thereto; an aqueous solution containing monoammino boron trifiuoride at therate-of from about 15.0to 400 poundsrof compound per acre.

d'. ,A composition. characterized by its ability to selectively kill crabgrass in the-presence of other desirable lawn grasses consisting of an aqueous-solution containing from 0.1.0 to' 1 by weight of monoammino boron trifluoride and from-0.10 to 1% by weight of a wetting agent, the-balance of the composition. being. water.

5.; The method of selectively killing crab grass which comprises thestepsof spraying onto crab grass infected turf an aqueous solution containing from 0.10 to 1%" by weight of monoammino boron triiiuoride and from 0.10- to 1% by weight of'a non-ionic wetting agent dissolved in water at therate of'about 25 to pounds-of the monoammino boron trifiuoride per acre.

6'. An herbicidal composition consisting of monoamminoiboron trifluoride and sufiicient wetting agent to impartto an aqueous solution containing from 0:1 to 1%- by weight of the monoammino boron trifiuoride a surface tension not exceeding about lO'dy-nesper centimeter at 23 C.

7 An herbicidal composition consisting of approximately 75 parts; by weight of monoammino boron trifluorideand from 10. to 50 parts by weight of a non-ionic wetting agent.

FRANK J. SOWA.

REFERENCES CITED The" following references are. of record in the file of this patent:

UNITED. STATES PATENTS .Nmnher: Name- Date 2,277,744 Cuprey -et. a1. Mar. .31, 1942 2,390,941 Jones Deer 11., 1945 2,392,859 Meuli Jan. 15, 1946 2,394,916 Jones Feb. 12-, 1946 2,544,141 Donleavy Mar. 6, 1951 FOREIGN PATENTS Number Country Date 10,450 Great Britain May 17, 1906 of 1905 OTHER REFERENCES Journal of American Society of Agronomy, Apr. 1941, page 367. 

1. THE METHOD OF KILLING WEEDS WHICH COMPRISES THE STEP OF APPLYING THERETO AN AQUEOUS SOLUTION CONTAINING FROM ABOUT 0.10 TO 10% BY WEIGHT OF MONOAMMINO BORON TRIFLUORIDE AT THE RATE OF ABOUT 16 GALLONS OF SOLUTION PER 1000 SQUARE FEET. 